Evaluating age in the field triage of injured persons

Abstract

Study objective: We evaluate trauma undertriage by age group, the association between age and serious injury after accounting for other field triage criteria and confounders, and the potential effect of a mandatory age triage criterion for field triage.

Methods: This was a retrospective cohort study of injured children and adults transported by 48 emergency medical services (EMS) agencies to 105 hospitals in 6 regions of the western United States from 2006 through 2008. We used probabilistic linkage to match EMS records to hospital records, including trauma registries, state discharge databases, and emergency department databases. The primary outcome measure was serious injury, as measured by an Injury Severity Score greater than or equal to 16. We assessed undertriage (Injury Severity Score ≥16 and triage-negative or transport to a nontrauma center) by age decile and used multivariable logistic regression models to estimate the association (linear and nonlinear) between age and Injury Severity Score greater than or equal to 16, adjusted for important confounders. We also evaluated the potential influence of age on triage efficiency and trauma center volume.

Results: Injured patients (260,027) were evaluated and transported by EMS during the 3-year study period. Undertriage increased for patients older than 60 years, reaching approximately 60% for those older than 90 years. There was a strong nonlinear association between age and Injury Severity Score greater than or equal to 16. For patients not meeting other triage criteria, the probability of serious injury was most notable after 60 years. A mandatory age triage criterion would have decreased undertriage at the expense of overtriage, with 1 patient with Injury Severity Score greater than or equal to 16 identified for every 60 to 65 additional patients transported to major trauma centers.

Conclusion: Trauma undertriage increases in patients older than 60 years. Although the probability of serious injury increases among triage-negative patients with increasing age, the use of a mandatory age triage criterion appears inefficient for improving field triage.

Figure 1

Schematic of the primary sample and “triage-negative” subgroup.

Figure 2

Schematic of constructing the database at each of 6 sites *This figure represents a slightly modified version of a figure from Newgard CD et al. Evaluating the Use of Existing Data Sources. Probabilistic Linkage and Multiple Imputation to Build Population-Based Injury Databases Across Phases of Trauma Care Acad Emerg Med(In Press). Reprinted with permission from Academic Emergency Medicine

Figure 3

Age-based evaluation of under-triage among injured patients transported by EMS * *We defined “under-triage” two ways: (1) the percentage of patients with serious injury (ISS ≥ 16) that did not meet field trauma triage criteria and (2) the percentage of patients with ISS ≥ 16 that were not transported to a Level I/II trauma center. Results were qualitatively similar when transport destination (Level I/II) included subsequent interhospital transfers. The full sample (n = 260,027) includes all injured patients transported by EMS with use of multiple imputation to impute missing ISS for patients without a matched hospital record The matched-only sample (n = 89,441) includes only patients that matched to a hospital record.

Figure 4

Unadjusted and adjusted probability of Injury Severity Score (ISS) ≥ 16 by age for all injured patients (n = 260,027) and for patients not meeting triage criteria (n = 215,915). *Multivariable logistic regression models (adjusted estimates) included the following variables age, prehospital Glasgow Coma Scale score, prehospital systolic blood pressure ≤ 90 mmHg, intubation attempt, prehospital intravenous line placement, mechanism of injury and site.

Figure 5

Figure 5-A. Unadjusted and adjusted odds ratios for Injury Severity Score (ISS) ≥ 16 by age group for all injured patients and for patients not meeting field trauma triage criteria. Figure 5-B. Unadjusted and adjusted odds ratios for Injury Severity Score (ISS) ≥ 16 by age group for all injured patients and for patients not meeting field trauma triage criteria. *Odds ratio for age categories are adjusted for the following covariates prehospital Glasgow Coma Scale score, prehospital systolic blood pressure ≤ 90 mmHg intubation attempt, prehospital intravenous line placement, mechanism of injury and site. † For unadjusted odds ratios, the 95% confidence interval reaches statistical significance (does not cross one) for patients 0–15 years, 61–65 years and over 75 years; error bars are omitted for clarity. ‡ For unadjusted odds ratios, the 95% confidence interval reaches statistical significance (does not cross one) for all patients over 55 years; error bars are omitted for clarity.

Figure 5

Figure 5-A. Unadjusted and adjusted odds ratios for Injury Severity Score (ISS) ≥ 16 by age group for all injured patients and for patients not meeting field trauma triage criteria. Figure 5-B. Unadjusted and adjusted odds ratios for Injury Severity Score (ISS) ≥ 16 by age group for all injured patients and for patients not meeting field trauma triage criteria. *Odds ratio for age categories are adjusted for the following covariates prehospital Glasgow Coma Scale score, prehospital systolic blood pressure ≤ 90 mmHg intubation attempt, prehospital intravenous line placement, mechanism of injury and site. † For unadjusted odds ratios, the 95% confidence interval reaches statistical significance (does not cross one) for patients 0–15 years, 61–65 years and over 75 years; error bars are omitted for clarity. ‡ For unadjusted odds ratios, the 95% confidence interval reaches statistical significance (does not cross one) for all patients over 55 years; error bars are omitted for clarity.